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A242765 a(1) = 2; for n>1, a(n) = product of digits of (a(n-1)^2). 0
2, 4, 6, 18, 24, 210, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Table of n, a(n) for n=1..72.

EXAMPLE

6 is in the sequence because 4^2=16 and 6*1=6.

18 is in the sequence because 6^2=36 and 3*6=18.

Other similar sequences, starting from 3, 5 and 7, respectively:

. 3, 9, 8, 24, 210, 0 (0 continued);

. 5, 10, 0;

. 7, 36, 108, 144, 0.

MATHEMATICA

a[1] = 2; a[n_] := a[n] = Times @@ IntegerDigits[a[n - 1]^2]; Array[a, 100] (* Jean-Fran├žois Alcover, May 29 2014 *)

NestList[Times@@IntegerDigits[#^2]&, 2, 80] (* Harvey P. Dale, Aug 23 2017 *)

CROSSREFS

Cf. A163522.

Sequence in context: A064402 A268577 A075229 * A073664 A088174 A052930

Adjacent sequences:  A242762 A242763 A242764 * A242766 A242767 A242768

KEYWORD

nonn,base,easy

AUTHOR

Vincenzo Librandi, May 29 2014

STATUS

approved

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Last modified August 13 00:27 EDT 2020. Contains 336441 sequences. (Running on oeis4.)